This invention relates to annular electrical connector assembly and more particularly to a sealed annular electrical connector assembly for multiple electrical devices having annular contact rings.
It is known to measure cylinder pressure of a combustion engine utilizing a non-intrusive pressure sensing device as disclosed in U.S. Pat. No. 5,329,809 granted to Mark C. Sellanu, Robert G. Plyler and Andrew F. Rodondi, Jul. 19, 1994. A spark plug well within a cylinder head typically mounts threadably and grounds electrically the sensing device. The pressure sensing device comprises a cylindrical metal sleeve forming a concentric channel to mount, seal and shield an annular sensing element within. The sleeve projects the length of the sensor at the inner diameter and provides electrical shielding from high voltage interferences caused by the ignition wires passing through the center of the sensor body.
Sealing the annular sensing element is a lower bonnet having electrical insulating properties. Above the lower bonnet is an electrical contact ring. The contact ring makes electrical contact with the sensing element via a metallic trace which is electrically insulated from the metallic sleeve. Above the contact ring is an upper bonnet. The sleeve flares outwardly above the upper bonnet forming a leading edge. The leading edge holds the sensor assembly together axially.
The annular contact ring of each sensor is electrically isolated from the metallic sleeve portion of each sensor and is connected to an electrical interface. The electrical interface and leading wires must be protected and sealed from the harsh environment surrounding the spark plug wells of a combustion engine cylinder head. In order to achieve a reliable seal, the electrical connector must be capable of adjusting to changing temperatures and varying tolerances.
Accordingly, the present invention is an electrical connector assembly encircling each spark plug along the length of a combustion engine cylinder head. The electrical connector assembly has a tray containing a plurality of apertures. Each aperture is centered over a pressure sensing device positioned within a cylinder head well about a spark plug. Extending through each aperture is an electrical connector having a housing. The housing has an upper portion and a lower portion with a terminal located between. In resilient engagement between the upper portion and an upper bonnet of the sensing device is an upper seal. The terminal is in electrical contact with a contact ring of the sensing device preferably via tabs protruding inboard of a ring of the terminal. The upper seal forces resiliently the tabs against the contact ring. Preferably, in resilient engagement between the lower portion and a lower bonnet of the sensing device is a lower seal. The combination of the upper seal and the lower seal protects the electrical contact of the tabs and the contact ring from the environment.
The upper portion of the housing is preferably secured to a shoulder of the tray by a flange which permits the housing to float radially during assembly and fixes the housing axially within the aperture. Preferably, a wire lead extends from the terminal through the tray. Each wire lead from each electrical connector is electrically connected to a common panel mounted electrical connector snap fitted to the tray. A shield plate having a plurality of holes, wherein each hole is centered over each aperture, is preferably snap fitted above the wires to the tray. Further, the shield plate is bolted to the cylinder head thereby providing an electrical path to ground electrical interference signals. Once bolted, the housing is radially fixed within the aperture. The spark plugs are accessible through the holes of the shield plate.
A feature of the invention is that the electrical contact between the tabs and the contact ring is isolated and protected from the environment.
Another feature of the invention is an electrical connector with a floating housing to conform to varying tolerances.
Yet another feature of the invention is a shield plate which diminishes high voltage interference and permits maintenance access to the spark plug.
These and other objects, features and advantages of the invention will become more apparent from the following description of a preferred embodiment taken in conjunction with the accompanying drawings.